Light source for recording sound on film



I April 2, 1935;

s. c. WHITMAN LIGHT .SOURCE FOR RECORDING SOUND ON FILM Filed April 18, 1932 MEP|| flcll INVENTOR.

.E an I VI u I I I r ATTORNEYS.

Patented Apr. 2, 1935 UNITED STATES PATENTOFFICE-1 nmn'r sooner: roa' necoanme scum)- ONFILM W c. Whitman, Jackson Heights, N. Y. Application April is, 1932, Serial No. 05,991

21 clai This invention relates to new and useful improvements in the art of recording sound on film and more particularly to a high-frequency gaseous conduction lamp to produce the desired result, this application being a continuation in I part of my copending application, Serial Number 507,220, filed January 27, 1931.

An object of the invention is cording lamp of high photographic value.-

to produce a re- A further object of 'theinvention is to provide a lamp whose light source is of appropriate size,

shape, and brilliancy for the optical reduction in recording sound on film.

Another object of the invention is to provide a recording lamp of long life and of con struction.

Still another object of the invention provide, a recording lamp lated by a magnetic field.

to. which can be modu- With these and other objects in view, my' invention consists in the novel features of construction, combination; and arrangement parts as will be hereinafter referred to and more particularly pointed out in the specification and claims.

In the accompanying drawing forming a part of this application:

Figure 1 is a diagrammatic view showing my improved lamp, partly in section, in operative relation to a lens and film;

Figure .2 is a side elevation of a lamp constructed in accordance Figure 3 is acentral through;

with my invention, parts being shown in section: 1-.

vertical section there- Figure 4 is a horizontal section asseen on, the

[line 4-4 of Figure 3;

Figure'5 is a side elevation,

of a slightly modified form 'of lamp;

Figure 6 is a vertical section therethrough;

'and 1 partly in section,

Figure 'I is a horizontal section on the line 1-1 of Figure 6.

In the process of recording sound on mm by the modulated glow-discharge .lamp method definite advantages may result from the use high-frequency current as the activating lamp .means.

By reason the associated and utilizing of the selection and arrangement such high frequency current,

recording apparatus enerating have found it oftendesirable to separately control the high-frequency current activating the recording lamp with respect to the audible sound frequencies to be recorded, or conversely,

rectangular flat electrodes ll,-

. cally quire' variations in both area and intensityof the light source, corresponding with the sound variations' v 15 In the present invention, a recordinglamp is provided by means of which all the above described conditions may be fulfilled.

Referring more particularly to'the drawing,

Figures 2 to 4 inclusive set forth a form of my 20 invention wherein 8 is a transparent envelopeof glass'or other suitable material into whichis sealed a mounting stem 9. The stem '9 carries an upstanding tubular projection. III as shown clearly in Figure 3. A cylindrical insulating 25 member VII of refractory material is provided which carries a tubular downwardly extending projection I 2, said projection; snugly engaging the upstanding projection l0 and serving to support the insulating member I l in an upright position, The insulator H is provided-with alongiv tudinal slot Ila intersecting the upper and lower peripheral faces thereof and extending across the full diameter of said insulator, as clearly shown in Figures 3 and 4. .The inner op faces of the segments of the insulator ll formed by the slot Ila are recessed at 13 to receive'the said, electrodes having lead-wires l5 connected thereto which extend downwardly through the 9. These 40 electrodes are arranged parallel and of substantially 'of the same size, shape, and area. A heliformed inductance coil designated by the numeral I6 is provided, the convolutions-of which are wound on the peripheral surface of the insulator ll andheld in fixed position by the'spiral groove l'l providedon the surface of saidinsulator as clearly shown in Figure 3 of the drawing.

The lowermost convolution of the helical inductance coil I6 is connected to the lead-wire ll which" extends downwardly through the; stem 8. The uppermost convolution extends laterally out-. .ward, is bent downwardly as at I! passing through the tubular protective member 2., and

is connected with the lead-.wireil which passes Id downwardly through the stem 9. A drop of mercury 22 is provided to produce the mercury vapor necessary to the operation of the lamp. The lamp is evacuated in the usual manner and an inert gas such as argon admitted to a pressure of approximately ten millimeters of mercury.

Figures to 7, inclusive, illustrate another modification of my invention. In this adaptation, the insulator 23 is rectangular in cross section, and is provided with a centrally disposed longitudinal slot extending the full length of the insulator, designated by the numeral 24. The

end walls of the slot 24 are provided with spacing grooves 25 to receive and hold the electrodes 25 in abutting relation to the side walls of said slot as clearly shown in Figure 7.

In other respects, the structure of this modification is generally similar to that of the lamp heretofore described. In Figure l, I have illustrated a lamp, constructed in accordance with the first described form of my invention showing its operative relation to lens elements 26 and a film 21.

Lamps constructed in accordance with my present invention possess great versatility in their applications to sound recordingby highfrequency means. A substantially steady high frequency current may be impressed across the electrodes shown at It and the steady light produced as a result may be modulated by passing current at audible frequencies through the inductance coil l6. It'will be noted at this point that the construction of the insulator prevents undesirable discharges from occurring between the lead wires of the electrodes and the lead wires of the inductance coil, and confines the glow between the electrodes forming the desired light source as regards shape. Thiscareful shielding is essential to the construction of agaseous discharge lamp utilizing high frequency energy. Since the two electrical circuits are entirely distinct from each other, the relations one to the other as manifested by the light output of the lamp may be easily studied, controlled and adjusted.

In the case where the sound modulatedhigh frequency current is used directly on the lamp electrodes such controlcannot be directly achieved but must be accomplished through the media of the ,various amplification 'and modulation circuits whereinit is usually difiicult to determine the exact efiect of one variable upon another.

If it is desired, a steady'direct current may be used to activate the lampand sound modulated high frequency current passed through the inductance coil. As a result of the separate circuits means for automatically controlling the value of the activating current with relationto the modulating current maybe introduced.

Again, it may be desired to use high-frequency modulated current in the inductance coil and activate the inner electrodes with high-frequency current of a different wave length in order to produce a heterodyne frequency for monitoring processes associated with the apparatus or to concurrently control other separate apparatus. It will be noted that a; control or modulating I current impressed upon the inductance coil establishes a magnetic field which includes the inner electrodes. A glow discharge occurring between .the two innerelectrodes' is effected by this magnetic field and may be controlled by it. This M9511), brought about by the novel constructional nfeatures of my invention, may be used to perstrength of the magnetic field, the intensity of the glow discharge being simultaneously increased and decreased. With appropriate opti cal means the light from such a fluctuating discharge can be utilized to produce a variable area-variable density sound record on the film. Inherent defects in the photographic properties of the film emulsion may be compensated for by providing a sound record of this type.

Due to the fact that the steady current activating the recording lamp andthe modulating current are supplied from separate circuits no distortion can result from faulty impedance matching between lamp and amplifier output.

While I have shown'and described preferable adaptations of my invention, I do not wish to be limited thereto, it being understood that various changes in form, proportion, and minor details of construction may be resorted to, within thescope of the appended claims.

Having thus described the invention, what I claim is: w

1. In a gaseous conduction lamp for recording-sound on film, a pair of parallel electrodes of substantially equal areas, and magnetic fieldgenerating means surrounding the same.

2. In a gaseous conduction lamp for recording netic field generating means surrounding said electrodes.

5. In a gaseous conduction lamp for recording sound on film, a pair of electrodes, an insulator substantially enclosing the same, and a magnetic field-generating means mounted on said insula-' tor and surrounding said electrodes.

6. In a gaseous conduction lamp for recording sound on film, a pair of electrodes, an insulator substantially enclosing the same, anda magnetic field-generating means mounted on said insulator and surrounding both the insulator and said electrodes.

7. In a gaseous conduction lamp for recording sound on film, a' pair of plane parallel electrodes of equal areas, an insulator substantially enclosing thesame, and a magneticfield-generating means mounted on said insulator and sur- Jnounted on said insulator and surrounding said rounding both the insulator and said electrodes.

lator substantially enclosing said'electrodes provided externally with a helical groove, and an inductance coil having turnsconforming to and fitting within said helical groove. I

11. In a gaseous conduction lamp for recording sound on film, a pair of plane parallel electrodes of equal areas, an insulator substantially enclosing the same provided with an external helical groove, and an inductance coil having turns conforming to and fitting within said hell-- cal groove. v 12. In a gaseous conduction lamp including a glass envelope, a-stem therein, a projection on said stem, a pair of electrodes, lead wires thereto, an insulator slotted to receive said electrodes and mounted on said projection, and means generating a magnetic field mounted on said insulator. and surrounding same.

13. In a gaseous conduction lamp, a transparent envelope, an anode and a, cathode centrally disposed in said envelope,. an inductance coil within, said envelope surroundingsaid anode and said cathode, and common means for supporting said anode, said cathode and said inductance coil, said means being inside said inductance coil and surrounding said anode and said cathode.

14. In a gaseous conduction lamp, an envelope,

a pair of substantially parallel plane electrodes disposed in said envelope, and a helical inductance coil disposed in said envelope with its axis substantially'parallel with the faces of said elec-[ trodes.

15. In agaseous conduction lamp, an envelope,

formed'by said slotting, and an inductive winding disposed inside said envelope and being wound on said insulating member and surrounding said electrodes,

16. In a gaseous conduction lamp, an envelope, an insulating member disposed in said envelope and being internally apertured to provide a channel having two substantially parallel faces andextending substantially the length of said insulating member but not. occupying its entire cross section, a pair of electrodes respectively disposed I on said internal parallel iacesoisaid' insulating mide and said member, and an inductive winding inside said envelope andbeing wound onsaidinmember and surrounding said electrodes. f 1'1. In a gaseous conduction lamp, a transparent envelope, an anode and a cathode disposed I in said envelope adjacent each other to form a principal determined electron path therebetween, and a helical inductance coil within said envelope surrounding said anode and said cathode-arid having its axis substantially perpendicular to said principal electron path.

I 18. In a gaseous conduction lamp, a; transparent envelope, an anode and a cathode disposed in said envelope adjacent each other to form a principal determined electron path therebetween, and means within said envelope surrounding said cathode and said anode for generating an electromagnetic fleldsubstantially perpendicular to said principal determined electron-path.

19. In'a gaseous conduction lamp, a transparent envelope, an anode and a cathode disposed in said envelope symmetrically with reference to a plane of symmetry positioned between said anode and said cathode, and an inductance coil 'within' said envelope surrounding said anode and said cathode and generating an electromagneti 25 field whose line of direction lies in said plane of symmetry.

20. In a gaseous conduction lamp, a transparent envelope, an anode and a cathode disposed in said envelope adjacent each other to form a principal determined electron path therebetween.

means within said envelope surrounding said cathode and saidanode for generating an electromag'netic field substantially perpendicular to, said principal determined electron path, and a pair of control leads extending .through said envelope and connected to the terminals of said means. Y

g 21. In'a gaseous conduction lamp, a transparent envelope, an anode and a cathode centrally disposed in said envelope, an inductance coll within said envelope surrounding said anode and said cathode, a pair of control leads extending through said envelope and connected to the terminals of said inductance coil, and common .means for supporting-said anode, said cathode,

and said inductance coil, said means being inside said induetance coil and cathode.

s'rawan'r c. 

